External heat exchanger question.

[MarkandCath]

I am an Electrician and I have been asked to wire up the electrics for a friend's Biomass boiler that is located in an outbuilding. I am deeply concerned about the planned heat exchanger in the home and I have a question.

The plan is to install a small heat exchanger (shoe box size) inside the house and pump 90C water from the biomass through it. The output would then be pumped around the radiators. To get up to temperature this heat exchanger will have to put more thermal energy into the system than the radiators can release and given the low input temperature and small size of the heat exchanger it seems impossible to me.

Like I said, I am a sparky, but I would like the thoughts of a heating engineer as this doesn't make sense to me. Thanks.

 

[MNW67]

I'm not a HE. But I know that plate heat exchangers are incredibly efficient at transferring heat from one liquid to another. This is the plate HX from a combi boiler. It's tiny!

 

[Exedon]

Correctly sized its fine all very normal
We regularly fit them on large old systems typically with large steel pipework and cast rads.
Separates old mucky system from shiny new boiler.

 

[MarkandCath]

Thanks for the replies. I didn't realise these water to water heat exchangers were so efficient. Well I will wire the pump in about a week and we will see how it runs. Thanks again.